Q. The formula of potash alum is
A) $K_{2}SO_{4}.Al_{2}\left( SO_{4} \right)_{3}.24H_{2}O$
B) $K_{2}SO_{4}.Al_{2}\left( SO_{4} \right)_{3}.18H_{2}O$
C) $K_{2}SO_{4}.\left( NH_{4} \right)_{2}SO_{4}$.$18H_{2}O$
D) $Na_{2}SO_{4}.Al_{2}\left( SO_{4} \right)_{3}.24H_{2}O$
Explanation
(a)
Alum is a double salt having general formula $M_{2}SO_{4}M_{2}^{'}\left( SO_{4} \right)_{3}.24H_{2}O$ where $M$ is monovalent metal and $M^{'}$is trivalent metal. Potash alum has potassium (K) as monovalent metal. Potash alum is
$\ \ \ \ \ \ \ \ \ \ \ \ \ K_{2}SO_{4}.Al_{2}\left( SO_{4} \right)_{3}.24H_{2}O$.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.